Researchers at the University of Maryland, College Park have printed transparent transistors on transparent paper. The finished device is flexible, up to 84% transparent, and in theory this could be the first step towards green, paper-based electronics.

As we’ve covered before, printing computer circuits isn’t overly difficult — you just need to find the right conductive and semiconductive inks (which can be tricky), and then print them out on a suitable substrate until you have a transistor. Because these ink-based printed circuits are very thin, though, the smoothness of the substrate is very important. When you’re dealing with layers of ink that are a few nanometers thick, any blemish on the substrate is enough to disrupt the flow of electrons and break the circuit.